Zirconium salts of carboxylic acids are useful as dryer catalysts in substances such as paints and coatings. Zirconium carboxylate can also be used to increase the viscosity of oil and to form greases. According to "Zirconium Chemistry in Industry" In Journal of Chemical Education Pgs. 604-610; VOl. 39; No. 12; DEC. 1962, aqueous zirconyl and basic zirconyl chlorides react with alkali soaps to form zirconium soaps, generally containing one zirconium atom per fatty acid radical. The zirconium acylates or soaps produced are soluble in non-polar solvents, and can be used to increase the viscosity of oils and to form greases.
Several methods for preparing zirconium soaps are described in U.S. Pat. No. 3,036,101 including: (1) Reacting the sodium salt of the carboxylic acid with a water soluble inorganic zirconium salt such as zirconium oxychloride or sodium zirconium sulfate. According to this teaching the resulting water insoluble zirconium soap is extracted by solution in a suitable organic solvent and the solvent is then removed by distillation. (2) A method reacting water-insoluble zirconium carbonate, derived from a water-soluble zirconium inorganic salt and sodium carbonate is agitated with the organic acid. The resulting zirconium soap is then dissolved in the organic solvent and removed by extraction.
The disclosed invention in U.S. Pat. No. 3,036,101 calls for reacting water insoluble zirconium basic sulfate with a monocarboxylic acid in the presence of an alkali agent, said alkali agent being present in a concentration stoichoimetrically equivalent to the sulfate content of the zirconium basic sulfate. In accordance with this process the alkali agent can consist of alkali metal hydroxides, alkali metal carbonates, alkali earth metal oxides and alkali earth metal hydroxides. In a preferred embodiment this reference indicates that the organic acid is partially neutralized with the alkali equivalent to the sulfate and zirconium carboxylate is formed by the reaction of the partially neutralized organic acid with the zirconium basic sulfate.
U.S. Pat. No. 2,739,905 specifically describes the production of zirconyl 2-ethylhexanoate by the double decomposition of water soluble zirconium salt such as zirconium oxychloride or zirconium sodium sulfate with an alkali 2-ethylhexanoate, or by the fusion of insoluble zirconium carbonate with an excess of 2-ethylhexanoic acid. Unreacted 2-ethylhexanic acid is then removed.
Generally, the commercial production of zirconium carboxylate requires a stoichiometric excess of carboxylate relative to the zirconium. Typically the carboxylate to zirconium equivalency ratio is set at a minimum of 1.6:1.
The instant process has advantages over prior art methods in that the zirconium carboxylate product can be prepared in one process step in high yields and with high metal content, i.e. a very low carboxylate to zirconium mole ratio is achieved. In this regard, it has furthermore been discovered that with the excess of basic carbonate as employed by the instant process, the production of undesired and insoluble zirconium by-products is avoided.